This is a plug-in diffuser, much like Glade Plug-ins or Febreze unstoppables. Unlike either Glade or Febreze, this diffuser has absolutely no scent whatsoever so it's a good idea to keep an eye on it around the 30 day mark for replacing. Anxiety: We have two senior dogs, both with anxieties such as separation anxiety, for one. In one dog this product seems to ease this, but he also benefits from a book on Audible when no one is around - go figure! (It has to be an audio book, he just does not care for music!) The other dog resorts to pacing, like a lion, until she exhausts herself, finally collapsing and falling asleep. Additionally, every evening our boy was having anxiety attacks that would come out of nowhere. He'd whine, pant heavily, and pace for hours. This was the reason we decided to give this product a chance well over a year ago; hopeful the pheromones would either reduce or ease his anxieties altogether. Our former Vet would not even entertain the idea that our dog was going through hell every evening, so we have had to find a solution, through trial and error, on our own. This product has definitely reduced those anxiety attacks down to about one per week. A huge and glorious improvement for him, and us. Thunderstorms/Rain: With continued use, it seems as though this might actually be working for my senior boy. He no longer cries, bursts through pet gates and bedroom doors looking for comfort. Instead he quietly retreats to our lower level, resurfacing about 10 minutes later, and curls up on his bed to nap out the worst of it. It's too soon to tell if this helps our girl, as we've only had one thunderstorm since she came to live with us. Fireworks/other loud noises: Last summer, this made little to no difference in how well my jittery guy handled the noise. We haven't had our old girl long enough to know how she'll react to this type of racket but will keep these on hand just in case. We recently bought these refills for two reasons: 1) it's spring and thunderstorms are starting in abundance and 2) our senior girl joined our home. Because she wakes in the middle of the night and begins pacing anywhere between an hour to two hours, we thought (or rather, hoped) this diffuser would be of some benefit to her. It's been plugged in for the last 60 hours and so far it has not helped with her nervous, middle of the night pacing. It wouldn't be fair to say this isn't working for her as I have little history on this formerly, terribly abused dog. Her environment is still new to her and I feel as if she needs more time to recover from being abandoned, neglected, and beaten. She is a sweet, loving girl who has already bonded with us, but her issues seem deep seated. We will give her time, both with her new home and this diffuser, to see if there is any improvement and / or benefit. Overall, as a repeat buyer, I would recommend with a caution to buyers that just because it might not work for you doesn't mean it's some sort of scam. Your furry friend might have deeper psychological issues, or it might be something/one in your environment making Fido uneasy.